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Old April 28th 06, 03:44 PM posted to rec.radio.shortwave
John Plimmer
 
Posts: n/a
Default Transmitter splatter

RHF
In earlier years I must have owned every type of antenna
tuner/preselector that was on the market.
The MFJ I found were so badly made of such cheap parts that they were
frankly awful.
Then I had an expensive Japanese Mizuho and finally a ham made me a really
nice one tube amplifier/tuner.

I must say though, that for use on holidays with my portables the old Grove
Mini Tuner was great. A really useful little box of tricks that did wonders
for maximising signals off a short wire 30/40 foot long (I'm not in favour
of hanging too much wire on a portable).

But then I started experimenting with the simple home brew magnetic matching
transformers and they outperformed all the fancy knob twiddling
tuners/preselectors by far, apart from there ease of use (no knob twiddling
and nothing to adjust at all).

I did experiments with various magnetic matching transformers I had and
found 9:1 the best for my needs on the BCB mediumwave band and the Tropical
bands. The 4:1 matching transformers worked well listening to international
broadcasters above 10 Mhz.

The 9:1 magnetic matching transformers I mainly use with my 1000 foot
beverage antenna's, but it also worked superbly on my suburban Windom
antenna which was only 55 foot long but I managed to get it up 40 foot high.

I don't think the length of wire attached to the magnetic matching
transformer matters at all - I have used them from 50 foot long on holidays
from hotel rooms to 1000 foot long beverages on serious DXpeditions. I think
what matters is that 4:1 favours reception in the upper HF band and 9:1 is
very good lower down the band.

Some of my pals who own Drake R8 series RX's run their longwires direct into
the shack and couple up to the 500 Ohm input of the Drake. But to me that is
silly, as if you look at the Drake workshop manual you will see that the 500
Ohm input on the Drake is terminated into a 9:1 transformer anyway, so it
is much better for noise abatement to terminate your longwire 30/40 foot
away from the shack/building and then run a coax into the RX and terminate
it into the 50 Ohm connector on the RX.

--
John Plimmer, Montagu, Western Cape Province, South Africa
South 33 d 47 m 32 s, East 20 d 07 m 32 s
RX Icom IC-756 PRO III with MW mods
Drake SW8 & ERGO software
Sony 7600D GE SRIII
BW XCR 30, Braun T1000, Sangean 818 & 803A.
GE circa 50's radiogram
Antenna's RF Systems DX 1 Pro, Datong AD-270
Kiwa MW Loop
http://www.dxing.info/about/dxers/plimmer.dx

"RHF" wrote in message
oups.com...
John Plimmer,

I would agree for the Shortwave Listener (SWL) who does
not want to get in to a lot of extra boxes in the Shack and
the resulting confusion of : ? Which Knob To Turn Next ?

The simple Matching Transformer between the Antenna
and the Coax Cable feed-n-line is the single best item
to add to the External Antenna to Coax to Radio System;
except for a good earthen Grounding Point.

NOTE - It is Interesting that you identify the use of
the 9:1 Matching Transformer for the lower reaches
of the spectrum AM/MW Band Tropic Bands and
such and the use of a 4:1 Matching Transformer
for above 10 MHz.

Question - Which respect to which type and size of
Antenna or Antennas do you make this statement ?

i want to know - iane ~ RHF
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